The phrase "hand onto" implies an act of gripping, holding, or keeping something. Antonyms for "hand onto" would be words that indicate the opposite action, such as release, let go, abandon or relinquish. These words suggest a conscious decision to separate oneself from the object being held, perhaps because it is no longer needed, desired or useful. The action of releasing or letting go can be symbolic of moving on, accepting change, or simply freeing oneself from the burden of attachment. Therefore, knowing the antonyms for "hand onto" is useful when expressing your intention of getting rid of something or accepting the end of a situation.